langchain-twosio 0.1.3

LangChain tools for 2s.io — pay-per-call AI agent APIs on Base via x402.

langchain-twosio

LangChain tools for 2s.io — pay-per-call AI agent APIs on Base via the x402 protocol.

No signup. No API keys. No monthly fees. Just a USDC-funded EVM wallet on Base mainnet. Each call settles per-request in USDC.

pip install langchain-twosio

import os
from langchain_twosio import get_twosio_tools

# private_key must be an EVM key (0x…) holding USDC on Base mainnet.
tools = get_twosio_tools(private_key=os.environ["EVM_PRIVATE_KEY"])

# Plug into any LangChain agent:
from langchain_openai import ChatOpenAI
from langgraph.prebuilt import create_react_agent

agent = create_react_agent(ChatOpenAI(model="gpt-4o-mini"), tools)
result = agent.invoke({
    "messages": [("user", "Find recent patent filings for 'neural network beamforming'.")]
})

The agent picks the right 2s.io endpoint, calls it, pays in USDC, and returns the result — transparent to your model.

What's in the box

Each tool wraps one 2s.io endpoint with a clear description and a typed pydantic args schema. The curated set covers the highest-leverage workflows:

Tool	Endpoint	What it does	Price
twosio_patents_search	patents.search	USPTO patent application search	$0.0018
twosio_papers_search	papers.search	Unified arXiv + PubMed + Semantic Scholar search	$0.0024
twosio_law_case_search	law.case-search	US court opinion discovery (~9M opinions)	$0.0036
twosio_law_case_verify	law.case-verify	Citation anti-hallucination check	$0.006
twosio_law_sanctions_check	law.sanctions-check	OFAC SDN screening (KYC/AML)	$0.0048
twosio_wikipedia_summary	wikipedia.summary	Wikipedia REST API summary	$0.001
twosio_weather_zip	weather.zip	US NWS current weather by ZIP	$0.0012
twosio_geocode_address	geocode.address	Address → lat/lon (LocationIQ)	$0.001
twosio_ai_summarize	ai.summarize	URL → concise summary (Tier 2, LLM-backed)	$0.0225
twosio_crypto_gas_oracle	crypto.gas-oracle	Live EVM gas oracle	$0.001

The full 2s.io catalog has 39 endpoints. To use one not in the curated set, build a tool manually:

from langchain_twosio import twosio_tool
from langchain_twosio._endpoints import EndpointSpec, Param
from twosio import TwoS

client = TwoS(private_key=os.environ["EVM_PRIVATE_KEY"])

custom = twosio_tool(client, EndpointSpec(
    name="twosio_dns_lookup",
    short_name="dns.lookup",
    description="Resolve a hostname against public DNS resolvers.",
    sdk_path=("dns", "lookup"),
    params=[
        Param("name", str, "Hostname to resolve."),
        Param("type", str, "Record type (A | AAAA | MX | TXT | NS).", required=False),
    ],
))

The full live catalog: https://2s.io/api/directory · OpenAPI: https://2s.io/api/openapi.

Filters

# Only the legal tools:
tools = get_twosio_tools(private_key=KEY, include=["law.case-search", "law.sanctions-check"])

# Everything except the LLM-backed (Tier 2) ones:
tools = get_twosio_tools(private_key=KEY, exclude=["ai.summarize"])

How payment works

Every tool call runs through the underlying 2sio SDK, which:

1. Hits the 2s.io endpoint.
2. Receives HTTP 402 Payment Required with an x402 envelope (price + recipient + EIP-3009 challenge).
3. Signs the transferWithAuthorization with your private key.
4. Retries with the signed payload.
5. Returns the response. The meta.settlement block in each result includes the on-chain tx hash.

You only pay for successful calls. Failed calls (4xx / 5xx) don't settle.

License

MIT.

Links

• 2s.io: https://2s.io
• Source: https://github.com/2s-io/sdk
• Issues: https://github.com/2s-io/sdk/issues
• Underlying SDK: 2sio on PyPI